A solid electrolytic capacitor is constituted by an electrical conductor (anode body) as one electrode, a dielectric layer formed on the surface layer of the electrode, and the other electrode (semiconductor layer) provided thereon. In the manufacture of a polymer solid electrolytic capacitor, forming of the dielectric layer on the anode body by chemical conversion and forming of the semiconductor layer thereon by electropolymerization are sequentially performed. Generally, a plurality of anode bodies are electrically connected in parallel, and such treatment as anodic oxidation and electropolymerization is carried out on the anode bodies at one time.
In the case of forming a semiconductor layer on a plurality of anode bodies, the following problem occurs because respective anode bodies are not always homogeneous and also the semiconductor formation rate can be vary among the anode bodies. That is, the value of current flowing through each of the anode bodies cannot be constant, and in an extreme case, one anode body becomes defective (short-circuited state), and the current concentrates on the one anode body while almost no current flows through the other anode bodies. In light of the above, the inventors of the present invention have proposed the method of forming a semiconductor layer by subjecting chemically-converted anode bodies to constant current electropolymerization by means of circuits including constant current sources (Patent Document 1; JP 2005-244154 A (WO2005/006360 A2)).